Code

#include <iom328p.h>
#include <io.h>
#include <interrupt.h>

#define xtal 16000000UL
#define baud 9600
#define UBRR_Value ((xtal / (baud * 16UL))) - 1

void setup_Usart(void){

	//Set-up Baudrate
	UBRR0 = UBRR_Value;

	//Enable Reception and Transmission
	UCSR0B |= (0 << RXCIE0) | (0 << TXCIE0) | (1 << RXEN0) |
		(1 << TXEN0);

	//Set-up Asynchronous, 8-bit, No Parity, Stop bit
	UCSR0C |= (0 << UMSEL00) | (0 << UMSEL01); //Asynchronous

	UCSR0C |= (1 << UCSZ01) | (1 << UCSZ00); //8-bit
	UCSR0B |= (0 << UCSZ02);

	UCSR0C |= (0 << UPM01) | (0 << UPM00); // No-Parity
	UCSR0C |= (0 << USBS0); // 1 end bit

	UDR0 = 0; //Make sure the UDR0 is empty

}

void writeUART(unsigned char data){
	while(!(UCSR0A & (1 << UDRE0))){
		//Wait for something to be transmitted
	}
	UDR0 = data;
}

unsigned char readUART(void){
	while(!(UCSR0A & (1 << RXC0))){
		//Wait for something to be read
	}
	return UDR0;
}

int main(void){

	int ptr=48; //Position pointer and counter for the array

	setup_Usart();
	//sei();

	while(1){

		//Lire un nombre entre 1 et 3 caractère
		while(!(readUART() & '\r')){
			writeUART(ptr);
			writeUART(0x0d);
			writeUART(0x0a);
			ptr++;
		}
	}
}